/*
 * Copyright (C) 2015 Square, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.squareup.javapoet;

import static com.squareup.javapoet.Util.checkArgument;
import static com.squareup.javapoet.Util.checkNotNull;

import java.io.IOException;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;

import javax.lang.model.SourceVersion;
import javax.lang.model.element.ElementKind;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.Modifier;
import javax.lang.model.element.VariableElement;

/** A generated parameter declaration. */
public final class ParameterSpec {
	public final String name;
	public final List<AnnotationSpec> annotations;
	public final Set<Modifier> modifiers;
	public final TypeName type;
	public final CodeBlock javadoc;

	private ParameterSpec(Builder builder) {
		this.name = checkNotNull(builder.name, "name == null");
		this.annotations = Util.immutableList(builder.annotations);
		this.modifiers = Util.immutableSet(builder.modifiers);
		this.type = checkNotNull(builder.type, "type == null");
		this.javadoc = builder.javadoc.build();
	}

	public boolean hasModifier(Modifier modifier) {
		return modifiers.contains(modifier);
	}

	void emit(CodeWriter codeWriter, boolean varargs) throws IOException {
		codeWriter.emitAnnotations(annotations, true);
		codeWriter.emitModifiers(modifiers);
		if (varargs) {
			TypeName.asArray(type).emit(codeWriter, true);
		} else {
			type.emit(codeWriter);
		}
		codeWriter.emit(" $L", name);
	}

	@Override
	public boolean equals(Object o) {
		if (this == o)
			return true;
		if (o == null)
			return false;
		if (getClass() != o.getClass())
			return false;
		return toString().equals(o.toString());
	}

	@Override
	public int hashCode() {
		return toString().hashCode();
	}

	@Override
	public String toString() {
		StringBuilder out = new StringBuilder();
		try {
			CodeWriter codeWriter = new CodeWriter(out);
			emit(codeWriter, false);
			return out.toString();
		} catch (IOException e) {
			throw new AssertionError();
		}
	}

	public static ParameterSpec get(VariableElement element) {
		checkArgument(element.getKind().equals(ElementKind.PARAMETER), "element is not a parameter");

		TypeName type = TypeName.get(element.asType());
		String name = element.getSimpleName().toString();
		// Copying parameter annotations can be incorrect so we're deliberately not
		// including them.
		// See https://github.com/square/javapoet/issues/482.
		return ParameterSpec.builder(type, name).addModifiers(element.getModifiers()).build();
	}

	static List<ParameterSpec> parametersOf(ExecutableElement method) {
		List<ParameterSpec> result = new ArrayList<>();
		for (VariableElement parameter : method.getParameters()) {
			result.add(ParameterSpec.get(parameter));
		}
		return result;
	}

	private static boolean isValidParameterName(String name) {
		// Allow "this" for explicit receiver parameters
		// See https://docs.oracle.com/javase/specs/jls/se8/html/jls-8.html#jls-8.4.1.
		if (name.endsWith(".this")) {
			return SourceVersion.isIdentifier(name.substring(0, name.length() - ".this".length()));
		}
		return name.equals("this") || SourceVersion.isName(name);
	}

	public static Builder builder(TypeName type, String name, Modifier... modifiers) {
		checkNotNull(type, "type == null");
		checkArgument(isValidParameterName(name), "not a valid name: %s", name);
		return new Builder(type, name).addModifiers(modifiers);
	}

	public static Builder builder(Type type, String name, Modifier... modifiers) {
		return builder(TypeName.get(type), name, modifiers);
	}

	public Builder toBuilder() {
		return toBuilder(type, name);
	}

	Builder toBuilder(TypeName type, String name) {
		Builder builder = new Builder(type, name);
		builder.annotations.addAll(annotations);
		builder.modifiers.addAll(modifiers);
		return builder;
	}

	public static final class Builder {
		private final TypeName type;
		private final String name;
		private final CodeBlock.Builder javadoc = CodeBlock.builder();

		public final List<AnnotationSpec> annotations = new ArrayList<>();
		public final List<Modifier> modifiers = new ArrayList<>();

		private Builder(TypeName type, String name) {
			this.type = type;
			this.name = name;
		}

		public Builder addJavadoc(String format, Object... args) {
			javadoc.add(format, args);
			return this;
		}

		public Builder addJavadoc(CodeBlock block) {
			javadoc.add(block);
			return this;
		}

		public Builder addAnnotations(Iterable<AnnotationSpec> annotationSpecs) {
			checkArgument(annotationSpecs != null, "annotationSpecs == null");
			for (AnnotationSpec annotationSpec : annotationSpecs) {
				this.annotations.add(annotationSpec);
			}
			return this;
		}

		public Builder addAnnotation(AnnotationSpec annotationSpec) {
			this.annotations.add(annotationSpec);
			return this;
		}

		public Builder addAnnotation(ClassName annotation) {
			this.annotations.add(AnnotationSpec.builder(annotation).build());
			return this;
		}

		public Builder addAnnotation(Class<?> annotation) {
			return addAnnotation(ClassName.get(annotation));
		}

		public Builder addModifiers(Modifier... modifiers) {
			Collections.addAll(this.modifiers, modifiers);
			return this;
		}

		public Builder addModifiers(Iterable<Modifier> modifiers) {
			checkNotNull(modifiers, "modifiers == null");
			for (Modifier modifier : modifiers) {
				if (!modifier.equals(Modifier.FINAL)) {
					throw new IllegalStateException("unexpected parameter modifier: " + modifier);
				}
				this.modifiers.add(modifier);
			}
			return this;
		}

		public ParameterSpec build() {
			return new ParameterSpec(this);
		}
	}
}
